Method and apparatus for orienting wood strands into parallelism

Abstract

A method and apparatus is described for use in producing a wood product comprising at least one layer of binder-coated wood strands oriented into parallelism by causing the strands to fall through elongated, parallel spaces defined by a plurality of generally rigid plates or flexible belt stretches located in vertical planes and parallel to each other above a moving support. The distance from each plate or belt stretch to the next adjacent plate or belt stretch is less than the average length of the strands. In one embodiment, adjacent, generally rigid plates reciprocate in opposite directions relative to each other. In another embodiment, adjacent belt stretches of an endless, flexible belt move in opposite directions with respect to each other. The upper edges of the plates and belt stretches have a number of spaced projections which operate to turn the strands which span two or more plates or belt stretches until the strands are aligned with the spaces therebetween and fall into such spaces toward and onto the moving support.

I claim: 
     
       1. A method of orienting wood strands into parallelism on a moving support to form a mat thereon comprising: providing a group of elongated, generally parallel spaces above the support with each pair of adjacent spaces having a movable boundary therebetween and extending to a predetermined depth and with each boundary having a plurality of spaced projections on the upper margin thereof; directing a mass of loose wood strands toward said group of spaces from above the same so that the strands aligned with the longitudinal axes of the spaces will gravitate therethrough and onto said support; moving each pair of adjacent boundaries in opposite directions relative to each other along respective, generally straight paths to cause corresponding projections to engage those strands which span the distance between the boundaries and to turn such strands into alignment with respective spaces, the speed of movement of the boundaries relative to speed of movement of the support being sufficient to cause upended strands having first ends engaging the strand mat therebelow and second ends engaging adjacent boundaries to be turned into substantial alignment with the longitudinal axes of respective spaces before the movement of the support can cause disorientation of the strands. 
     
     
       2. A method as set forth in claim 1, wherein said providing step includes forming an assembly of generally rigid plates, said moving step including reciprocating said plates. 
     
     
       3. A method as set forth in claim 1, wherein said providing step includes presenting a plurality of parallel stretches of an endless, flexible belt, said moving step including at least partially wrapping said belt around a rotating member. 
     
     
       4. A method as set forth in claim 1, wherein said boundaries are moved at a speed greater than the speed of the support and extend transversely to the direction of movement of the support. 
     
     
       5. A method as set forth in claim 1, wherein said moving step includes shifting said boundaries longitudinally of the direction of movement of the support. 
     
     
       6. A method as set forth in claim 1, wherein said providing step includes positioning the lower margins of said boundaries in proximity to and spaced from the support, the distance between said support and the lower margins of said boundaries increasing in the direction of support movement. 
     
     
       7. Apparatus orienting wood strands into parallelism with each other as they fall toward a moving support comprising: a plurality of spaced, parallel, generally rigid plates; means coupled with said plates for mounting the same above the support for movement relative thereto along generally straight paths with each plate being movable in a direction opposite to the direction of movement of each adjacent plate, each plate having an upper margin provided with a plurality of spaced, strand engageable projections thereon; and means coupled with said plates for moving adjacent plates in opposite directions along respective straight paths at a speed relative to the speed of movement of the support sufficient to rotate wood strands which span the upper margins of two or more plates into alignment with the longitudinal axes of the spaces between the plates and sufficient to cause upended strands having first ends engaging the strand mat therebelow and second ends engaging adjacent plates to be turned into substantial alignment with the longitudinal axes of respective spaces before the movement of the support can cause disorientation of the strands. 
     
     
       8. Apparatus as set forth in claim 7, wherein the projections extend more than 1/4-inch above the upper margins of the plates, the height of each plate being approximately equal to the maximum length of the strands. 
     
     
       9. Apparatus as set forth in claim 7 wherein said plates are divided into two groups, said mounting means including a frame for each group respectively, and a tensioning device for each plate, said frames being movable relative to each other and in opposite directions in response to the operation of said moving means. 
     
     
       10. Apparatus as set forth in claim 9, wherein each frame has a pair of spaced end members, said plates substantially spanning the distance between and being secured at their ends to corresponding end members of respective frames and held in tension. 
     
     
       11. Apparatus as set forth in claim 7, wherein is included a movable support below said plates, said support being declined relative to the lower margins of the plates in the direction of support movement. 
     
     
       12. Apparatus as set forth in claim 7, whereby the plates and the projections are less than 1/8-inch in thickness. 
     
     
       13. An apparatus as set forth in claim 7, whereby the total throw of adjacent plates is larger than twice the distance between adjacent projections. 
     
     
       14. Apparatus as set forth in claim 7, said projections having triangular sawtooth shapes. 
     
     
       15. Apparatus as set forth in claim 7, the projections extending perpendicular to the upper margins of said plates and having rectangular shapes. 
     
     
       16. Apparatus for orienting wood strands into parallelism with each other as they fall toward a support comprising: flexible belt means defining a plurality of spaced, parallel, generally planar strand guide members; means coupled with said belt means for mounting the same above the support to position the guide members for movement relative to the support along generally straight paths with each guide member being movable in a direction opposite to the direction of movement of each adjacent guide member, each guide member having an upper margin provided with a plurality of spaced, strand engageable projections thereon; and means coupled with said belt means for moving adjacent guide members in opposite directions along respective straight paths at a speed relative to the speed of movement of the support sufficient to rotate wood strands which span the upper margins of two or more guide members into alignment with the longitudinal axes of the spaces between the guide members and sufficient to cause upended strands having first ends engaging the strand mat therebelow and second ends engaging adjacent guide members to be turned into substantial alignment with the longitudinal axes of respective spaces before the movement of the support can cause disorientation of the strands. 
     
     
       17. Apparatus as set forth in claim 16, wherein said belt means comprises a single, endless, flexible belt defining more than two of said guide members. 
     
     
       18. Apparatus as set forth in claim 16, wherein said belt means comprises a plurality of endless, flexible belts, each belt defining a respective pair of said guide members.